impersonation and acting, even though they go hand in hand, sometimes.
Impersonation is the easier of the two, in my humble opinion, of course. I don't disagree at all that getting physical disabilities correct is a must.. I just think doing so is not that difficult. ANY awkward, or unusual physical action will get noticed.
Now in Hoffman's case, and other actor's performances as well.... he studied the man he was portraying, or his character was based on, with ferver... every motion.. that's impressive. But, sorry to say, I don't think that's all that difficult... or I should say, one of the lesser difficulties in a performance.
One of the top 'impersonating' performances was Robin Williams in Mrs. Doubtfire... he received rave reviews, and it was VERY entertaining... but for me the 'impersonation' aspect wasn't that impressive.
I get ya. And I think yours would definitely be the majority opinion. - JamesJM